Angular unit test http call - test is splicing up the query param into query params

Using Angular 12, I have this service which has this call

    consumeGetPatientsToReconcile(query) {
      const host = this.appConfigService.apiBaseUrl;
      const url = `${host}/foo/bar`;
                          
      const obs = this.http.get(          
        url,
        { params: query }
      );
      return obs.pipe(tap((data) => this.reconcileMainService.setReconcileData(data) ));
    }

and I have this unit test

    it('should consume patients reconcile api', () => {
      service.consumeGetPatientsToReconcile('page=1').subscribe((data) => {});
      const req = httpTestingController.expectOne('host/foo/bar');
      const foo = req.request.params.get('page')
      console.log(foo);
  
      httpTestingController.verify();
    });

but in the test it is splicing up the query params page

> Error: Expected one matching request for criteria "Match URL: host/foo/bar", found none. Requests received are: GET host/foo/bar?0=p&1=a&2=g&3=e&4==&5=1.

Also, it seems the param is missing in req.request.params.get('page')

You cannot pass directly a string as params property of options argument for HttpClient.get (or request in general).
It expects an object of type HttpParams, so you need to create one.
Your case is quite trivial so you can simply do

const obs = this.http.get(          
  url,
  { params: new HttpParams().set('page', '1') }
);

while for more complex situation, you can leverage HttpParamsOptions utilities like fromObject.

In general, I suggest to better type your code, and maybe rethink your project's structure, because that method returning a tapped observable is quite unusual and doesn't smell too nicely.